Over the years, there has been considerable recognition of the need to cool semiconductors, as, for example, diodes, rectifiers, transistors, etc. in a variety of different applications for such components. In general, this has been accomplished by mounting a semiconductor, usually in already encapsulated form, to a heat exchanger by such means as clamps, bolts, screws, etc. Exemplary of this approach are the following U.S. Letters Patents: U.S. Pat. No. 2,942,165 issued June 21, 1960 to Jackson; U.S. Pat. No. 3,275,921 issued Sept. 27, 1966 to Fellendorf; U.S. Pat. No. 3,361,195 issued Jan. 2, 1968 to Meyerhoff; U.S. Pat. No. 3,365,620 issued Jan. 23, 1968 to Butler; U.S. Pat. No. 3,437,132 issued Apr. 8, 1969 to Venema; U.S. Pat. No. 3,551,758 issued Dec. 29, 1970 to Ferree; U.S. Pat. No. 3,643,131 issued Feb. 15, 1972 to Scherbaum; U.S. Pat. No. 3,715,632 issued Feb. 6, 1973 to Warburton; U.S. Pat. No. 3,794,886 issued Feb. 26, 1974 to Goldman; U.S. Pat. No. 3,913,003 issued Oct. 14, 1975 to Felkel; U.S. Pat. No. 3,921,201 issued Nov. 18, 1975 to Eisele; U.S. Pat. No. 3,989,099 issued Nov. 2, 1976 to Hosono; U.S. Pat. No. 4,009,423 issued Feb. 22, 1977 to Wilson; U.S. Pat. No. 4,010,489 issued Mar. 1, 1977 to Boubeau; U.S. Pat. No. 4,023,616 issued May 17, 1977 to Scherbaum; U.S. Pat. No. 4,029,141 issued June 14, 1977 to Ferrari; U.S. Pat. No. 4,036,270 issued July 19, 1977 to Ahmann; U.S. Pat. No. 4,142,577 issued Mar. 6, 1979 to Kline; U.S. Pat. No. 4,178,630 issued Dec. 11, 1979 to Olsson; and U.S. Pat. No. 4,292,647 issued Sept. 29, 1981 to Lee.
While the approaches exemplified by the foregoing patents have achieved some degree of success, because they are basically an "add-on" structure for existing semiconductor components, they frequently are quite bulky both in size and in weight and have circuitous and/or unnecessarily resistive heat exchange paths which may employ inefficient thermal conductors and/or interfaces thereby impeding efficiency of heat transfer to a coolant.
Other semiconductor cooling arrangements using unencapsulated semiconductor wafers with heat exchangers as an integral part of the semiconductor package have been proposed in, for example, U.S. Pat. No. 4,079,410 issued Mar. 14, 1978 to Schierz and U.S. Pat. No. 4,209,799 issued June 24, 1980, also to Schierz. Proposals such as those of Schierz to some extent avoid the add-on nature of the heat exchanger in other prior devices but do not provide a means to cut down on bulk and are not particularly well suited for miniaturization. Moreover, though while the heat exchangers employed are not "add-on" types in the same sense as the previously identified prior art, they may be so-called add-on type heat exchangers in the sense that the joining method employed almost acts as the clamping elements such as bolts, screws, or the like used in other proposals. As a consequence, undesirably resistive heat exchange paths can still exist.
In the commonly assigned application of Niggemann, Ser. No. 411,059, filed Aug. 24, 1982, and entitled "Compact High Intensity Cooler", the details of which are herein incorporated by reference, there is disclosed a heat exchanger capable of substantial miniaturization and high thermal efficiency. Unlike conventional heat exchangers, that described by Niggemann can efficiently handle relatively high heat fluxes in a small volume heat exchanger having relatively low power requirements for pumping a heat exchange fluid. According to one math model, to achieve the same cooling achieved in one embodiment of the heat exchanger employing the principal of the Niggemann exchanger, at the same coolant temperature it would require a pressure differential of some 350 times that required by the Niggemann invention to achieve the requisite coolant flow in a conventional copper plate-fin heat exchanger with high density fin spacing. Thus, to achieve such a pressure drop flow rate, greater power requirements would be necessary.
The present invention, in one aspect thereof, seeks to take advantage of the invention of Niggemann in cooling semiconductors. In other aspects, the present invention seeks to overcome the bulk difficulties and inefficiently resistive heat transfer paths posed by the prior art.